Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have analyzed a series of Moloney murine leukemia (M-MuLV) envelope (env) protein fusions to the marker proteins invertase and placental alkaline phosphatase (PLAP), expressed in Psi2 retrovirus packaging cells. The yeast invertase protein, fused at its third amino acid residue to the amino-terminal signal sequence and 17 residues of the mature M-MuLV env protein, retained its enzymatic activity and was secreted from mammalian cells. However, env protein fusions to the C-terminal portion of invertase were inactive. In contrast, some, but not all, env protein fusions at the C-terminal region of PLAP were enzymatically active: PLAP fusions containing long C-terminal portions of env localized to the rough endoplasmic reticulum (RER) and possessed low enzyme activity levels, while fusion constructs containing relatively short portions of the M-MuLV env gene localized to the Golgi and had higher activity levels. Those proteins that localized to the Golgi also were processed, in part, to forms of 67 to 68 kDa, the size of the mature PLAP protein. Since PLAP ordinarily is transferred to a phosphatidyl-inositol glycan tail (PIG-tail) in the Golgi and then transported to the plasma membrane, it appears that Golgi-localized PLAP-env fusions are processed imperfectly. PLAP itself, when expressed in Psi2 cells, accumulated at the plasma membrane and, unlike the PIG-tailed Thy-1 protein, was not incorporated into virus particles. Thus, the reported incorporation of the Thy-1 protein into M-MuLV virions does not appear to be a consequence of its glycoprotein tail.
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PMID:Retroviral envelope protein fusions to secreted and membrane markers. 158 54

A leukemic mouse model was employed to elucidate the separate effect of leukemia and cytotoxic drugs on the jejunal mucosa and its associated digestive enzymes. The mitotic activity, depth of the crypt and villus-crypt quotient were not significantly changed in leukemic mice in comparison to normal mice. The mitotic activity and the depth of the crypt 48 h after 20 mg methotrexate (MTX)/kg were significantly reduced (p less than 0.01) in leukemic mice. Sucrase (p less than 0.001) and maltase (p less than 0.025) activities in the jejunum from leukemic mice were significantly elevated in comparison with non-leukemic controls. In both non-leukemic and leukemic mice, the dose-response curves for MTX administration revealed a significant decrease and a nadir in sucrase (p less than 0.001) and maltase (p less than 0.0025) activities at the dosage of 20 mg/kg. Thus, in the mouse model, leukemia per se does not contribute to significant diminution in small intestinal function. In the small intestine, MTX appears to be responsible for a decrease in the mitotic activity of crypt cells, depth of the crypt and diminished sucrase and maltase activities.
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PMID:Effect of leukemia and methotrexate on digestive enzymes in the jejunum of mice. 701 77